In disease treatment and prevention, early and reliable detection of pathology or the risk for developing pathology is invaluable. For instance, breast cancer is the second leading cause of cancer related death in women. Data indicate that ninety-six percent of women will survive five years if the cancer is localized, seventy-five percent will survive five years if the cancer is regional, and twenty percent will survive for that period of time if the cancer is metastasized. A method that can effectively and reliably identify breast cancer can lead to prompt treatments and improve the chances of survival for breast cancer patients.
Conventionally, pathology diagnosis typically involves the study of a biological sample, such as a biopsy of breast tissue, by a trained pathologist. In the past decade or so, however, applications of spectroscopy and microspectroscopy have made great advancements in the areas of clinical study. Several laboratories are currently actively investigating the potential of various spectroscopic techniques for screening and pathology diagnosis.
For instance, infrared microspectroscopy has been used in the study of cellular material. As is well known, infrared microspectroscopy involves illuminating a sample being studied with infrared light, and collecting the infrared light from a selected microscopic region of the sample to derive the infrared absorption spectrum of that region. Recently, Fourier Transform Infrared (FT-IR) spectroscopic imaging microscopy has been developed into a very powerful analytical technique. This technique uses a focal-plane array (FPA) detector attached to an FT-IR microscope to collect infrared images of an area of interest on the sample at various wavenumbers. The FPA detector includes an array (for example, 64×64 or 256×256) of pixels, each capable of independently detecting the intensity of infrared light impinging thereupon. A significant advantage of this technique as compared to more conventional infrared microspectroscopy is the parallel infrared detection using a relatively large number of pixels, which eliminates the need of point-by-point mapping of the sample. The parallel detection significantly reduces the time required to collect infrared images and spectra of a given sample.
Additional examples and direction of infrared microspectroscopic imaging are provided, for example, by Marcott et al., “Infrared Microspectroscopic Imaging of Biomineralized Tissues Using a Mercury-Cadmium-Telluride Focal-Plane Array Detector,” Cellular and Molecular Biology 44(1), 109-115 (February 1998); Lewis et al., “Fourier Transform Spectroscopic Imaging Using an Infrared Focal-Plane Array Detector,” Analytical Chemistry 67(19), 3377-3381 (Oct. 1, 1995); and U.S. Pat. No. 5,377,003 to Lewis. These references are hereby incorporated herein by reference.
Teachings in the prior art regarding the use of infrared spectroscopy for evaluation of cervical cells for malignancy or pre-malignant conditions are found, for example, in U.S. Pat. Nos. 5,976,885 and 6,031,232, both to Cohenford. The prior art also teaches a method for machine-based collection and interpretation of data on cells and tissues using vibrational spectroscopy. See, for example, U.S. Pat. No. 5,733,739 to Zakim, and U.S. Pat. No. 5,596,992.
Conventionally, infrared spectroscopic studies of biological samples have focused on cellular materials in the samples, with attempts to identify spectral features of the cells that could be linked to the presence of pathology. To date, many such attempts have been made. Yet, to the knowledge of the inventors of the present invention, no spectral features from extracellular materials in biological samples have been reliably correlated to common pathological conditions such as carcinoma.